1. Field of the Invention.
This invention relates generally to sprinklers and in particular to a rotary, pop-up sprinkler with a ball drive and a speed regulator.
2. Description of the Prior Art.
Sprinklers are used to irrigate vegetation in areas where natural precipitation is insufficient in amount or frequency. For example, grass-covered lawns, golf courses, parks and the like are frequently provided with sprinkler systems. Although above-ground sprinkler systems have a relatively low initial cost, they are usually set up and taken down for each use whereby their operation is relativley labor-intensive. Above-ground systems are subject to loss and damage from a variety of hazards and may contribute to personal injury and property damage if left out between uses.
In order to overcome the disadvantages of above-ground sprinkler systems, underground sprinkler systems have been devised which generally include a piping network buried in shallow trenches and a plurality of sprinkler heads located at predetermined locations to provide the coverage desired. Pop-up sprinklers which extend to use positions when subjected to water pressure and retract to storage positions are preferred because they avoid interference with maintenance equipment and permit the use of irrigated area.
Spray-type sprinklers generally include a plurality of nozzle orifices for dispensing water in a desired pattern comprising a circle or a segment thereof. Such sprinklers tend to have relatively few, if any, moving parts and are thus relatively inexpensive, but their spray patterns are more susceptible to wind deflection and they consume relatively large amounts of water per unit of irrigated area.
Rotary sprinklers, on the other hand, emit a stream or streams of water from one or more nozzle orifices which are rotated to achieve uniform coverage. Rotary sprinklers include motors which are generally driven by water pressure. For example, the Hunter U.S. Pat. No. 4,026,471 discloses a pop-up rotary sprinkler wherein the nozzle is driven by an impeller with a plurality of vanes. Since the water streams from rotary sprinklers are more concentrated, they can generally cover the same area with less water per unit of time than comparable spray-type units. Due to their lower water demand, more rotary sprinklers can be placed on a given piping circuit than spray-type sprinklers, whereby systems with rotary sprinklers tend to require less valving, trenching, piping and control devices such as timers, controllers and the like. The greater efficiencies which can be achieved with rotary sprinklers are particularly advantageous in applications where water pressure is restricted or water use is rationed.
Another type of rotary sprinkler motor is shown in the Reynolds U.S. Pat. No. Re. 25,942 and includes a ball for impacting a projection whereby the nozzle is incrementally advanced. The ball in such a sprinkler is driven in a circular pattern by a swirling vortex of water within the sprinkler body.
However, a problem with many prior art rotary sprinklers is that their motors tend to be relatively inefficient and thus require substantial water pressure for their operation, which reduces the overall throughput of the system. In particular, the bearing surfaces provided in most rotary sprinklers generate substantial amounts of friction and anti-rotational drag. A relatively large source of drag in many rotary sprinklers is a thrust bearing arrangement common thereto. The rotating element of most prior art sprinklers is extended by water pressure into engagement with a flange or ring which limits further extension and provides a thrust bearing surface. However, the water pressure tends to force the rotary nozzle element against the stop ring whereby frictional losses are encountered.
Yet another problem with many prior art rotary sprinklers relates to the introduction of foreign substances such as debris, sand and dirt into their bearing surfaces, which compounds their friction problems and can eventually clog or damage a sprinkler. To overcome such problems rotary sprinklers generally include either sealed bearings or a flushing arrangement such as that shown in the Miller et al. U.S. Pat. No. 3,334,817.
Heretofore there has not been available a rotary, popup sprinkler with the advantages and features of the present invention.